Field of the Invention
The present invention relates to a graph display apparatus and a graph display method and a storage medium for displaying graphs corresponding to function expressions.
Description of the Related Art
Recently, there are information devices such as portable terminals and portable phones and interfaces on display areas having touch panels are common. Therefore, it is possible to freely move contents of a display area according to a position and a movement of a user' touch on a corresponding touch panel.
Also, small-sized electronic computers (calculators) having a function of calculating function expressions are improved so as to be able to display graphs and figures, and, touch panels are provided in their display areas.
Technologies for enlarging or reducing or scrolling contents of a display area in such a display with a touch panel are considered as follow.
There is a technology for enlarging or reducing a graph in a calculator for displaying graphs corresponding to function expressions on a coordinate system having a predetermined coordinate range (for example, JP-A-562-186347). According to this technology, coordinate data on a range designated on a display area by user are stored, and if an enlargement key or a reduction key is pressed, a new coordinate range is generated based on the stored coordinate data, and a graph is enlarged or reduced to be displayed.
Also, there is a figure display control device having a function of scrolling graphs and coordinate axes (for example, JP-A-2004-126759). According to this technology, in a case where a graph, coordinate axes, and a trace pointer are displayed on a display area such that the trace pointer is on the graph, if a touch operation for moving the trace pointer toward the outside of the display area is performed on an end of a coordinate axis, the graph and the corresponding coordinate axis are scrolled such that the trace pointer is displayed inside the display area.
With respect to display control devices with touch panels according to the related art, some technologies for enlarging or reducing or scrolling contents of a display area in response to touch operations are considered; however, it is desirable to implement a more convenient display control technology.
The present invention was made in view of this problem, and an object of the present invention is to provide a more convenient graph display apparatus capable of controlling the state of display of a graph in response to a user's operation such that it becomes easier to see the graph.